Editor's Note:Matthew Lane is a Ph.D. candidate in mathematics at UCLA and is the founder of Math Goes Pop!, a blog focused on the surprisingly rich intersection between mathematics and popular culture. You can follow him on Twitter at @mmmaaatttttt.

Whether you are trying to make the best decisions for your fantasy baseball league, looking to capitalize on an opportunity in a fluctuating stock market or simply filtering through the results of a Google search, it is hard to deny that we are surrounded by more data now than ever before. As such, the task of organizing and drawing conclusions from data can be a challenge, but thankfully mathematics can, in many cases, rise to the occasion.

The application of mathematics to such a rapidly increasing pool of data, however, is not without controversy. For example, in February The New York Times published an investigation written by Charles Duhigg about the value of consumer data to major corporations, and how those corporations can use your data in an instinctively creepy way.

The company he focuses on is Target and its desire to identify pregnant women based on their shopping habits.

Target may have been too successful in this goal; as Duhigg writes, one teenage customer in Minneapolis was "outed" as being pregnant by a coupon mailer sent to her house. Her father was justifiably upset to see Target offering his underage daughter discounts on diapers and cribs, though he was perhaps more upset when he discovered Target knew more about his daughter's personal life than he did.

How is it possible for Target (or any company, for that matter) to draw such accurate conclusions about its customers from their shopping behavior? While the exact procedure is undoubtedly complex (Duhigg makes mention of Target performing some mathematical wizardry to assign each female customer a "pregnancy score"), the fundamental ideas are worth considering. In essence, what we are looking for is a way to assign a probability to an outcome (e.g. pregnancy) that is flexible, and can change as we learn more information (e.g. shopping habits). One way to do this is to apply Bayes' Theorem, a powerful result that allows us to modify the likelihood of some hypothesis as we obtain more information.

Let's consider the theorem in the context of Target and pregnancy. Suppose Target knows that at any given time, roughly 2% of its female shoppers are pregnant. A certain product, maybe it's a type of lotion, is particularly popular among pregnant women; to pull some numbers out of a hat, let's say that based on past consumer behavior, Target knows eight out of every 100 pregnant women will buy this lotion, while only one out of every 100 nonpregnant women will buy it. If you are a woman who buys this lotion, then essentially you are increasing the likelihood you are pregnant in the eyes of Target.

Bayes' Theorem tells us how to explicitly compute the probability that a woman is pregnant if she buys this item, by considering the ratio of the number of women who are both pregnant and buy the lotion to the number of women who simply buy the lotion (regardless of whether they may be pregnant).

With the numbers given above, the likelihood that a woman who buys the lotion is pregnant rises from 2% to just more than 14%; that's a sevenfold increase in the probability, and all just from the purchase of a single item! Though 14% isn't particularly high, when these probabilities are compounded across dozens of different purchases, suddenly it seems much more reasonable that a retailer could accurately infer a great deal about a customer based on his or her purchase history.

From a mathematical standpoint, the above example is no different from a woman taking a particularly crude pregnancy test (I say "crude" because any pregnancy test that detects pregnancy in only eight out of every 100 pregnant women probably isn't going to sell too well). Purchasing the lotion is the same as having a positive test result, while not purchasing the lotion is the same as a negative test result. The difference, of course, is that when a woman takes a pregnancy test, she is opting in, and her test results will be as confidential as she wants them to be. The same cannot be said for a pregnancy test administered without her consent through an analysis of what she buys.

The moral here is that the very same mathematics, like the power of the Force in "Star Wars," can be used for quite different purposes. Learning your daughter is pregnant when she shows you a positive test result is very different from learning she is pregnant from a retailer that sent her a coupon book for maternity clothes. It's natural to feel uncomfortable at the thought of large companies trying to infer personal details about you, but I'd encourage you not to think of mathematics itself as the problem. Indeed, this onslaught of data also has many wonderful applications (see, for example, the hunt for an Earth-like planet outside our solar system).

Instead, it is the process of data collection itself that ought to raise people's eyebrows. So, if your eyebrows are higher than normal, it may help to try to shop more locally and pay with cash. Of course, taking a few math classes to try to better understand what these companies are doing couldn't hurt either.

As a side note, the Joint Policy Board of Mathematics made April Mathematics Awareness Month. Every year a different subject is explored through the lens of mathematics; some of my favorite topics in recent years include the intersection of mathematics and sports (2010), voting (2008), and art (2003).

This year, the theme is "Mathematics, Statistics, and the Data Deluge." While it's a bit of a mouthful, it is certainly topical.

soundoff(127 Responses)

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April 27, 2013 at 8:41 pm |

tilted uterus

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April 23, 2012 at 1:34 pm |

mikefulton

The bit about how Target knows that pregnant women prefer a particular lotion leaves out important information. How did they generate that statistic in the first place? They would have to know, independent of any other data, if the women were pregnant or not. Did they conduct a poll to get initial data, and then use the statistics from that to make predictions about other women? It's kind of an important part of the equation here.

April 22, 2012 at 9:44 pm |

cam

I believe they simply looked at the past purchases of those customers who registered on their baby registry.

April 22, 2012 at 10:56 pm |

SkyKing

Big Brother is watching you.
George Orwell had it right, just missed the timing by 3 decades..

April 22, 2012 at 5:58 pm |

momxfour

I have four children. there's roughly 2 years between each child with the youngest now being in 3rd grade. Every couple months I get samples, coupons, and what my baby's milestones should be from diaper companies. Starts with newborn and works it's way up to training pants and potty training advice. I used cloth diapers for my younger 3 so I've not bought disposables in over a dozen years. I throw away the coupons and give my daughters the diapers to use on their baby dolls. According to major diaper companies, I should be newly pregnant with my 9th child any day now.

April 22, 2012 at 4:51 pm |

joesmith

ever frequent e-bay, they must do something similar, as they are bold enough to show you items you recently looked at..seems like an evasion of privicy to me..

April 22, 2012 at 4:38 pm |

farleyjc

I loved the article and it just goes to show how methodical marketing has become. I have a MBA and studied stats and had to incorporate stats in my grad research project. Nothing surprises me at this point. If Target put an X-Ray machine at the entrance doors it would not shock me.

No doubt my local Kroger grocery store has my number. I commonly receive coupon mailings based upon past purchases. That is OK, but what bothers me is when it is done on the Internet and I end up with 50 spams per day. Do one Google search using the word "financial" and the next day you have 25 mortgage companies telling you how great they are.

April 22, 2012 at 4:17 pm |

Lindalou

That whole theory doesn't hold up if I pay cash.

April 22, 2012 at 4:03 pm |

Polly

This is scary. Look beyond just the purchase of a pregnancy test. "The Broken Window" by Jeffrey Deaver is a murder mystery that is driven by consumer data and how it is used for legal and illegal purposes. It'll make you want to pay with cash, give up credit and debit cards, among other things!

April 22, 2012 at 4:18 pm |

pa

I would rather give small indecipherable information to companies like Target and get discounts. It is mutual and win-win for both. The Target like companies are legally bound by many local and federal laws. Try submitting this info to government agencies who makes those very laws and you would know how communism would look like.

April 22, 2012 at 3:24 pm |

Willie

I got my girlfriend knocked up last night. Is that okay with everybody?

April 22, 2012 at 2:15 pm |

jimmymax

Not really, Willie. Because you wouldn't know the very next day. You're not very bright, are you?

April 22, 2012 at 2:44 pm |

Edwin

My question: if the teen was already keeping this information from her parents, why didn't she just claim it was a case of bad advertising? We've all heard of the cases of dogs getting credit cards, babies getting ads for their weddings, elderly people getting coupons for bungee cord adventures and so forth...

If she wanted it a secret, she could easily have lied at that point, too and claimed it was simply a weird advertisement. The dad could have called Target and complained, and the daughter's name would have been removed from the pregnancy list...

April 22, 2012 at 1:45 pm |

Ummm

Right, what is the chance that the dad will find out that his daughter is pregnant as her belly grows bigger...

You see, one reason people should not lie is because it insults the other person's intelligence.

Why should t Target get blamed for the dad's inept parenting skills? If a kid has a secret such as pregnancy or drug use, the parent is to blame, not the informer. Parents would like to blame others for their own failures and ineptness. But this is a case of a dad now knowing his own family's pulse. He probably is one of those dads who have a mancave in the garage with his beer and big scree LCD TV. He probably talks to his daughter at most twice a week. He needs to close the mancave and stop getting drunk each night.`

April 22, 2012 at 1:24 pm |

5y5y5rcghchchfh

This is why i only use cash unless i cant(ie mail order when they need to know my address to ship the thing anyway).

I dont want want their targeted advertising garbage, and if that means i dont get a 10% discount...its well worth it! My income sucks, but my privacy is worth a lot to me.

April 22, 2012 at 1:21 pm |

Eric

Yet another reason why I use cash almost exclusively.

April 22, 2012 at 12:51 pm |

ericgoestoholland

Hey, another Eric that uses cash almost exclusively!

April 22, 2012 at 1:46 pm |

Lila

Not to be mean, but I don't think it takes a genius to come to the conclusion someone may be pregnant if they are purchasing a test and Palmer's oil(which I'm guessing is the lotion). Data collection has been studied in every possible way and it's still a failure, sorry. Not one company has been able to accurately figure out the perfect algorithm, all they do is collect, collect and collect some more. Examining purchases and guessing like Target did sometimes pays off like in this story. Sometimes it doesn't. Two companies send me catalogs because they assume I have kids, I don't, which was also based on my past purchases.

April 22, 2012 at 12:44 pm |

Edwin

Lila, data algorithms are NOT failures. You assume the goal is 100% prediction - it isn't. Like all advertisements, coupons, etc., the purpose is directed marketing.

If you send pregnancy coupons to 1000 people and only 8 are pregnant, that's a failed marketing technique (not only wasted advertising, but your company looks foolish). If you send 10 coupons and 8 are pregnant, that is a resounding success.

April 22, 2012 at 1:40 pm |

BrightGeorge

They don't have to be right all the time; they don't even have to be right most of the time. If it's profitable for them to be right -enough- of the time, it's profitable. Obviously you want to be as efficient (more often correct) as possible but you don't need to be anywhere near 100% for it to be worth doing.

April 22, 2012 at 1:41 pm |

Lila

The click thru rate online advertising is terrible. All the data collecting and invasion of privacy has not been worth it. Sorry but it has been a failure. However it won't stop companies from collecting data trying to figure out that magical algorithm unfortunately.

April 22, 2012 at 2:07 pm |

Annoyed

Lila, You are an idiot if you think these kinds of algorithms are failures. They are more accurate than you can know and more importantly, they are getting better as more and more information about people's behavior is recorded and becomes knowable.

April 22, 2012 at 4:23 pm |

Isaiah 40:31

Let's face facts – businesses are in business to make money. Retail makes ALL of it's money through suggestive selling. We are influenced by shelf positioning and where items are generally located in stores. There is a science to it all and math is at the center.

April 22, 2012 at 12:25 pm |

ATalbottt

One way to track their use of information is to always give a wrong address...such as changing the street number by 1..birthdate by 1, switch first and middle initials....Then you know where their getting their information! I've done that before and it's almost fun when they call asking for someone with your middle initial and confirming the address! I've done it often and then called them on it!

April 22, 2012 at 12:12 pm |

Shrikant

Can your CPM give you a list of OBs she has worked with berfoe that you can interview? Mine rec'd a practice for me that ended up being an awesome fit. If I transfer for a complication of pregnancy I'd be happy to see them, however if I have to transfer emergency style for a labor/birth complication chances are we won't make it to the hospital they practice at (30 mins away vs. a diff hospital 5 mins away). I like to think we get back up so that we won't need it. 😉

June 28, 2012 at 9:58 pm |

Ralph in Orange Park, FL

Some things are easy to figure out. Ever since I turned 65, I have been inundated with offers for Medicare supplement plans, estate planning, retirement communities and hearing aids. On the bright side, I have not gotten any coupons for Depends yet.

April 22, 2012 at 11:32 am |

Stock up on them!

Hi Ralph,

Hah your post made me chuckle. However, with the onset of the massive baby boomer retirement, it may be wise to stock up now 🙂

April 22, 2012 at 1:04 pm |

Willoww

Stores need to take a customer's age into account. It is possible that a pregnant teenager might have abusive parents, and those abusive parents may go off the deep end & physically hurt their teenage daughters. When you have a multicultural society and people immigrating to the U.S. from more conservative & traditional societies, it is imperative that stores consider safety above marketing to minors. If they do not, we will eventually see a news story in which a pregnant teen was murdered because someone in their family found out inadvertently.

April 22, 2012 at 11:32 am |

Isaiah 40:31

And how would the store determine the individual's age? Through shopping patterns?

April 22, 2012 at 12:19 pm |

Merc

How 'bout by not profiling them at all?

April 22, 2012 at 3:16 pm |

kdw31

Well they actually could guess age to some extent. For example as a 33 year old woman I don't shop in the juniors department. A teenager would shop almost exclusively for juniors clothing. They may also take demographic information when you sign up for credit cards or targets has some kind of debit card thing. If you use one of those then they don't even have to guess.

April 22, 2012 at 3:18 pm |

cc

Like the pregnancy test data collection is an 'opt-in' even though few people think of it that way-but that's because few people seem to think, period. I've only found one store that insists they need your name, etc when you pay cash-that's Radio Shack and I've given them plenty of false information to counter that stupidity. When I don't care if they track me I use credit/debit, frequent shopper cards, etc. When I do care, I pay cash.

April 22, 2012 at 10:49 am |

Peacepipe but don't smoke

The Republican's & Democrats should therefore learn that we will in the next 5 years
need more Medicare & Medicaid funding for senior' s as they live longer but will need
more nursing homes and non nursing homes to take care of them,we do know this is
coming to hit us all in the face as the kids say "big time" ,yet we hear that we have to
cut back on Federal/State healthcare , I guess we will have to put our old folks in the forest to live
with a couple of happy meals and then they can soon die there,... happy.

April 22, 2012 at 10:44 am |

Jyr78643

I recently got an ad booklet from Target in the mail- congratulating me for saying yes and including a coupon to get a $25 gift certificate for signing up for a wedding registry. I have no clue where they got the idea that I'm engaged, since the only things I buy there are cat litter, cat food, dog food, and cleaning supplies. How does that lead one to conclude I'm newly engaged?

April 22, 2012 at 10:26 am |

RonFromNM

Maybe they got the idea you're getting ready to clean up after a messy man and his dog?

April 22, 2012 at 12:07 pm |

t3chsupport

Seems like if they can do that, all they'd really have to do is find out who is buying pads and tampons who stops. Would certainly be easy to track if they used the store credit card. There's only 2 reasons women stop buying those things.

April 22, 2012 at 10:20 am |

Pam

Well. there are other reasons someone might not buy their stuff there. Maybe they bought some someplace else. maybe the last time they shopped for that stuff they bought in bulk at sam's club. Maybe they have been out of town for a while.

April 22, 2012 at 10:42 am |

Tom

So who’s monitoring the data of our spending as we use debit and credit cards? We have laws that protect our medical records for privacy; it seems we soon need laws that protect our privacy for spending. Google existence is threatened if we pass laws that make it illegal to monitor public network usage without consent. I think the future of these marketing firms is not a wise investment as well.

Electronic privacy is something we all need to keep an eye these days.

April 22, 2012 at 10:07 am |

RonFromNM

You hit the nail on the head. We need the equivalent of HIPAA to all other aspects of our life. These data mining activities without consent are a gross invasion of privacy.

April 22, 2012 at 12:10 pm |

tr

People get offended by this but tell every detail of their lives on Facebook...if you don't think they're collecting that data on you to use later you're not paying attention. It's actually one of the main reasons people are so hyped about their IPO...it's part of their stated business plan!

April 22, 2012 at 3:23 pm |

jeremyjones948

My statistics professor in B-school extolled us to forever remember Bayes Theorem, even if it is the one thing we get out of the MBA program. I have to say, it is a truly remarkable principle I have applied numerous occasions throughout my career to great effect.

April 22, 2012 at 10:07 am |

mikithinks

When you post on this site, you list your e-mail. Of course it will not be displayed, but used just how? I get e-mail for contacts with single hispanics, christians, hotties, and more. I also get all kinds of educational offers such as train to be a police officer. I'm most worried about that since I am 78 years old and it is scary to think the world needs my help in defending itself. These contacts are just noise, that go to everyone, and I don't put any information on the internet that I would not shout from my rooftop. OOPs 78. better stay off the roof.

April 22, 2012 at 9:26 am |

RonFromNM

That's why I keep a separate email address for website posting and product inquiries. And you're right, it's amazing the flood of offers from weird quarters that come... e.g. I get both offers to have an affair from one outfit and to seek the lord and redeem myself from another.

April 22, 2012 at 12:12 pm |

2tor

There are 8 trackers on this page alone. CNN sellls it just like everyone else.

April 22, 2012 at 12:23 pm |

2tor

hmmm, as soon as i posted that, one dropped off. I've never seen that happen. I'll have to watch that closer here in the furture.

April 22, 2012 at 12:31 pm |

fred

Just use cash and dont give them any other info or use those stupid cards.

April 22, 2012 at 9:23 am |

teacher1

I agree with the article. I'm past middle-aged now and when I shop, I always get coupons with my receipt for 'bladder protection' even though I don't buy them. They have my age stored in the computer and appeal to that characterization
of seniors. I really don't care–I pass them on to my friends who DO use bladder protection. Marketing is just a big business and anything I really don't want people to know, I don't put it on registration forms–social security number, real phone numbers, real addresses.

April 22, 2012 at 9:08 am |

jeantexas

Everything that I fill out that is not legal I put a different date if birth or bithday. Sometimes I was born in1900 sometime in 1970 I think it is NOB how old or young I am. Also I change my race.

April 22, 2012 at 10:11 am |

Mea

Google seems to think I'm a 24 year old male geek. Well, at least they got the geek part right.

April 22, 2012 at 9:01 am |

.

The solution to this problem is simple. Don't use a credit or ATM card and don't give them your address. And rip all the tracking chips off the box and thrown them on the front lawn of the girl who stole your boyfriend.

Better yet, don't shop Target.

April 22, 2012 at 8:47 am |

KC

Don't live in a small town, either. If you buy a pregnancy test or a dirty magazine, the cashier will call your mother before you get home. If you buy 5 bottles of booze every week, the gossip mill will hear about it. At least with Target, I'm a faceless name on a mailing list.

April 22, 2012 at 9:30 am |

cog

we live to serve the corporate machine

April 22, 2012 at 8:32 am |

.

It's either the corporate machine or the public sector union goon.

You're gonna serve someone.

April 22, 2012 at 8:48 am |

Mike Sabourin

absolute drivel!!!
Slow news day???

April 22, 2012 at 7:24 am |

LJ

The book "The Numerati" by Setphen Baker covers a lot of this type of stuff too.

April 22, 2012 at 7:20 am |

terri

Perhaps there is no mathematics involved. I would like to suggest a more direct relationship. I.e. Female who purchases pregnancy test with credit card gets tagged in Target's database.

April 22, 2012 at 7:12 am |

Show Me State

That is my thought exactly. If they paid by cash, there would be no way to track your purchases.

April 22, 2012 at 8:41 am |

.

They can still track everyone's purchase. There is a tracking chip on almost everything you buy, whether it's a 12 pack or box of tampons.

They know where you live.

And we're worried about da gubmint?

April 22, 2012 at 8:51 am |

Jan

Why you should always pay with cash and never use loyalty cards.

April 22, 2012 at 5:00 am |

Robert

Makes you wonder if the HIPPA laws should apply to cases like this as well?

April 22, 2012 at 2:57 am |

Mr Neutron

No, no it doesn't.

April 22, 2012 at 6:32 am |

terri

I heartily agree!

April 22, 2012 at 7:13 am |

terri

that HIPAA should apply...

April 22, 2012 at 7:14 am |

ajdsaiofjdsa

You hippa to the hoppa and you just don't stoppa?

April 22, 2012 at 3:48 pm |

Shree

There are so many ways by which companies can view customer's purchasing habits. For example a drug store where I live offers their store discount card and encourage us to swipe it regardless of whether the charges are going to be discounted. This way they are going to have access to my credit card (if allowed by law to view and assess) or the receipt for volume consumed in a day for internal stocking needs. It is hard to deny that data cannot be used or misused by such companies for either sending coupons to our residence or stocking the items on the shelves at the right rates.

Age of information. Even if one used cash if the receipts and store card are scanned each time, that would be a give away.

Nice thoughts from the article though. Enjoyed it!

April 22, 2012 at 2:53 am |

DR

Skynet is being built before our eyes. Science Fiction becomes fact. We are doomed.

April 22, 2012 at 1:30 am |

tmare

Target and the formula companies seem to decide that I am pregnant every couple of years. My kids are seven and eight years old and over the past few years I have received numerous boxes of formula samples and coupons as well as dozens of Target baby coupon books and gift cards in the mail. I still buy wipes because I find them useful and every baby shower gift that includes diapers and other useful items I have bought seem to trigger this. I'm not complaining because I usually pass them along to friends who are pregnant or have babies but I'm not so sure that their math is accurate.

April 22, 2012 at 12:47 am |

William O. B'Livion

PVT Consumer:

No, OB/GYNs and hospitals do NOT see patient data. That would, unless you *explicitly* give them permission, be illegal under HIPPA.

Sue-Helen: It is not an invasion of privacy. What you do in public is by definition not private. Doctors also do not take an "oath" of silence on any such thing. The only oath doctors (might still) take is the Hippocratic Oath, which has nothing to do with privacy.

April 22, 2012 at 12:26 am |

Fiona

I was "identified" as a probable mother some years ago by the catalog and coupon gross polluters. It was painful every time I got that stuff in the mail (and it still is, because I still receive it) because I desperately wanted children and was not so blessed. I request that mailings be stopped, but they always atart up again. I hope anyone who compiles those lists and send that junk out gets cancer. Do you know how much pain you cause?

April 22, 2012 at 12:26 am |

blinky

"I'd encourage you not to think of mathematics itself as the problem." lol, who would read this article and think that the fault lies with the number 14% for being bigger than 2%? this article reads like it was written for 10-year-olds.

April 21, 2012 at 11:55 pm |

Mark

Perhaps – but it does not hurt the public to know some of the mechanics of how retailers learn so much about them; most have never heard of many of these methods – so let them learn, no harm in that is there?

April 22, 2012 at 2:27 am |

Jack Splat

It's written at a 10-year-old level because that's roughly the equivalent level of mathematical understanding of the general population.

April 22, 2012 at 8:52 am |

CJ

How true! My personal pet peeve is when the commercial tells me something is 10 times smaller. How can a multiplier make something smaller?

Yeah, you can do that, but some stores with loyalty cards send out generous discounts ($10 off, or even a debit card with $10 or more on it) to the addresses on those forms. Safeway used to. So the laugh is on you, I guess.

April 22, 2012 at 12:30 am |

Reader

No, the joke isn't on him. By giving up $20 or $30 in free merchandise each year he is able to keep his privacy. For me, it's well worth giving up some shopping benefits. A few years ago there was a court case where Safeway was defending a slip-and-fall lawsuit and during discovery they claimed that the plaintiff was an alcoholic and might have been drunk when he slipped. When the defense attorney demanded where they got this information they settled. It is assumed that they looked at the products this customer purchased – probably a lot of alcohol – to determine how to attack him in the lawsuit. I don't think I would want Target to profile my health based on what I bought in the pharmacy.

April 22, 2012 at 1:18 am |

Mark

Fiona, the joke is not on him, he is exercising his right not to divulge personal information and made a decision that what they offer was not worthy of that privacy invasion.

April 22, 2012 at 2:28 am |

Dan

Why sign up for the loyalty card at all?

April 22, 2012 at 8:32 am |

KC

Because I spend enough at RiteAid every year to get 20% off on all my purchases there. That's a big chunk of change back in the pocket of someone on a fixed income.

April 22, 2012 at 8:58 am |

Jonny Oduya

Great article, Matt! Thank you. I totally accept the gist of the article, and the principle of privacy, etc. It raises the whole issue of the evolution of technology and how our (relatively incompetent and constipated) legislators are going to try to keep pace with the privacy issue vis a vis commerce/free market/technological advance, etc. But, in relation to this particular example it points out the absurdity of our culture and our laws when Target can be crunching numbers and figuring out when your daughter is pregnant, while she (AND HER PHYSICIAN) has absolutely NO responsibility–and can actually be penalized for divulging her "with child" status to her guardians; we are only half a step away from walking into an amoral hell. Money talks, that's all the culture of trash is about. We're all just numbers and noses to the powers that be. Hold your breath we're riding shotgun down an avalanche and no one's at the wheel, our moral GPS is broken and there's no one out there who can speak against the collective will of the people to fix it.

April 21, 2012 at 11:20 pm |

HenryMiller

I couldn't guarantee it, but I strongly suspect Google and other search sites use the same method–plus other things like inference engines–to profile people. If it bothers you that stores are collecting data on you, I'd strongly advise you not to use Google or any other search site.

April 21, 2012 at 11:19 pm |

Merlin

Hmm, maybe it could be utilized to search for intelligent life on this planet...

April 21, 2012 at 11:19 pm |

Col Breed

Just buy that stuff with cash. Untraceable. And don't use the store discount card for it either.

April 21, 2012 at 10:53 pm |

jo

i'm not ashamed of what I buy nor consider it a secret. The problem is that they use things like buying a lotion in combination with something else to make a pregnancy determination even though neither of the products are directly related. If I was buying certain vitamins, pregnancy test etc, then it would make sense. Frankly, I don't mind receiving targeted coupons based on what I buy – just don't think they've got that right yet.

April 22, 2012 at 7:28 am |

flopflipper

Bayes Theorem doesn't even cover the half of it. The analysis can go so much deeper than that.

April 21, 2012 at 10:51 pm |

Mark

Indeed very true, but consider it is a public audience not a math faculty – just understanding the basic concept of how math is used is sufficient to make the argument that stores use myriad technologies and algorithms to learn about us.

April 22, 2012 at 2:30 am |

Hassane

Most tests these days will tell you if youre pregnant from the day you are due. It will delenitify show up if you are 5 days over. Id get another test and f it comes back negative chances are you arent pregnant. They are really sensitive.I knew I was pregnant 3 weeks after my last period- and the test came back positive even when I took it before I was due to come on. Was this answer helpful?

July 1, 2012 at 2:40 am |

Kris

I stopped linking my store loyalty cards to my 'real' name/address/phone number when I realized that my grocery store could track my periods based on my purchase history of feminine hygiene products. THAT'S how they track us, not by some numerical statistics of who buys what. Damn debit card numbers!

April 21, 2012 at 10:37 pm |

sam

Oh my... honestly... who in the world cares about your periods? No one is browsing a giant spreadsheet about you and giggling about your menstrual cycle.

April 22, 2012 at 2:36 pm |

Hoosier

No it's not from your OBGYN. It's because your credit card purchases. Pregnant women stop buying hair dye, start buying vitamin B12, buy unscented lotion, etc. etc. Each purchase or lack there of zeros in on if she is preggers.

April 21, 2012 at 10:34 pm |

tomnikoly

I'm reminded of the scene in "Minority Report" where Tom Cruises' character walked into a department store and all the screens addressed him by name and offered products aimed specifically at him. Fiction, yes....but I'll bet a marketer or corporate sales exec somewhere had a wet dream.

April 21, 2012 at 4:29 pm |

Hoosier

We are not far from that. Your phone will soon have the option to let a retail outlet know who you are. When you walk up to a LCD screen it will tell you what sales maybe important to you.

Doctors and hospitals are definitely NOT doing it. They get your address information from your credit card. They figure out you are pregnant based on statistics. The original new York times article is excellent, albeit creepy.

April 21, 2012 at 9:25 am |

unowhoitsme

We no longer have a PERSONAL life. BIG BROTHER and all his friends knows all about us.

April 21, 2012 at 6:25 am |

Dear_D

I have read comments, but didn't get the point: what is soooo wrong with receiving discounts, samples of things for baby, catalogs etc. – being recognised as pregnant woman? Would be very happy if I am pregnant to get some discount, for sure. Apply that theoreme on me, please!!! :-))

April 21, 2012 at 1:52 am |

Sue-helen

They should offer a discount in that case to all pregnant mother's shopping in the store. Researching data about people and using it to peddle a product is spying and an incredible abuse of privacy. What about women who want their pregnancy kept secret or those who are carrying a sick or handicapped child, for whom pregnancy is a desperate challenge? When my children were little, I had a huge amount of company phone calls and even unwanted house calls from people selling everything from baby food to childrens books and surveys about childhood development. Someone gave them my information and information about my kids. I resented it!

April 21, 2012 at 4:14 am |

Mark

Dear_D, its simple really – its CREEPY, they did not have consent to gather information about her, they solicited her for things she did not ask for. Its not about the math, its about the intent and objective behind it that is the problem.

April 22, 2012 at 2:32 am |

Mr Neutron

When you signed up for their card you gave consent. try reading contracts before you just sign them.

it's all about targeted (no pun) marketing and how effective it is. Coming soon, targeted commercials in your home based on YOUR buying habits. It's closer than you think.

April 22, 2012 at 6:35 am |

jo

Because many of us are NOT pregnant. Just think of the marital issues it could cause too... For me it is a waste to receive things I don't need or want. It apparently already has cause family problems and awkwardness. It is one thing to get home depot coupons in the mail versus something as significant as being pregnant especially when it is based on flawed math...

April 22, 2012 at 7:18 am |

sam

If you receive an ad that assumes you are pregnant and you have to spend more than 10 seconds explaining to your partner that you aren't pregnant, then you might want to worry more about trust issues in your relationship than whether or not some company is collecting data on you for targeted ads.

April 22, 2012 at 2:40 pm |

Neutronstar

Pay for your purchases with cash – don't use your credit/debit cards – you remain completely anonymous. A major drug store chain wanted me to apply for and use their discount card on my purchases to save a few dollars – I declined and no longer shop there. A major supermarket chain has membership cards – I don't shop there either.

April 20, 2012 at 10:36 pm |

jo

crazy... I'm 47 with a 22 year old son. I recently started getting baby magazines and formula in the mail for no reason. Seems like the math might be alittle off...

April 20, 2012 at 10:17 pm |

Teri

Same here. My baby is 11. And, about 2 years ago, I started getting diaper and formula coupons in the mail. Even came home one day to a big box of formula samples on the porch.

April 20, 2012 at 11:45 pm |

Jerry

CVS likes to send me coupons for feminine hygiene products, Midol, and diapers; I'm a 47 year old GUY, I'm single, and my son is 25!

April 21, 2012 at 10:55 pm |

Sunny

I bought a few cans of powdered infant formula for a batch of newborn KITTENS. Now everytime I shop at CVS with my 'loyalty card' (for the discounts) I get more coupons for baby and kid stuff instead of ones for the useful products I got before. I don't need baby food and diapers - I need cat food and litter for my crew!

April 22, 2012 at 1:56 am |

Mark

It is a probability not a definite thing; there is still degree of randomness – so the math is sound, they know some will have no interest.

April 22, 2012 at 2:33 am |

Teresa

That seems like an invasion off privacy for doctors to sell lists off pregnant patients to companies.

April 20, 2012 at 9:11 pm |

Teri

The doctors aren't doing it. The stores are figuring it out by what you buy using your store credit card or rewards card. If you normally buy a box of tampons each month and then quit buying them and buy a pregnancy test and then buy a book about baby names. They've pretty much figured it out. Anybody who didn't realize the stores were tracking them all these years with these cards has been living with their head in the sand. Just think of rewards cards as "cookies" for the brick and mortar world.

Actually, Target knows who is pregnant because ob/gyn's (as well as hospitals) sell their pregnant patients data to companies like Gerber and Johnson & Johnson, which in turn sell their data with companies like Target. Otherwise, there is no way, even with mathematical theorems, could these companies get those names and address.

April 20, 2012 at 8:21 pm |

Sue-helen

Yes and it is disgusting. I know hospitals do it, but if Ob/gyn's are doing it too, then they are abusing their oath of silence concerning patient's privacy. If I found out that my doctor's office sold that kind of information, I would report them!

April 21, 2012 at 4:07 am |

DrSmith

If an OB/GYN discloses medical information about a patient without consent, they are violating HIPAA laws. OB/GYNs are not allowed to share any protected health information with a third party without express, written consent of the patient.

April 22, 2012 at 6:44 am |

Amy

Are you one of those tinfoil-hat people who forwards every chain email that comes to your inbox, and 'shares' every FB post that says it will donate $1 for every share so some kid with a serious disease can get free surgery? You seem pretty gullible.

April 22, 2012 at 8:39 am |

JohnS

@ Pvt Consumer: Hospitals and doctors are prohibited from provided any such information! They may make free gifts/samples (provided by merchants) available to discharging patients – – if patients choose to utilize the products or coupons, or complete questionnaires for additional freebies/coupons, that is their own decision.

April 22, 2012 at 11:13 am |

Xeno

If you have proof that this is being done, you need to report it, as that would be a huge HIPPA violation. If you don't have proof, I think you might be underestimating the power of math. Pay cash.

April 22, 2012 at 1:17 pm |

AMERICA 1st

Bip brother is watching us all!

April 20, 2012 at 7:15 pm |

Lurker

I also know your pregnant, because I went through your trash.

April 20, 2012 at 7:01 pm |

KC

Which is why my roommate took her pregnancy test in a brown paper bag to dispose of in a trash can in the park.
I keep my trash can at the sidewalk to reduce neighborhood litter, so it's always full of beer cans (I don't drink beer) and other things that I don't use myself.

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